Naruto is home to some of the strongest characters to ever appear in an anime - seriously, there are characters who can wipe out the planet with a single move, which isn't something that can be said for every show. But with so many outlandishly strong contenders, who are the most powerful Naruto characters?
Members of the Uchiha clan, a family known for their incredible eye based ability, crop up frequently. Sasuke Uchiha begins life as a child prodigy who can hold his own against adults, but he ends up gathering such a wide range of powers that he's almost godlike. Madara Uchiha follows a similar trajectory. But super-powered characters crop up outside of the Uchiha clan as well - Tsunade can not only heal herself and others with speed and precision, she can also split the ground open with her fists. And let's not forget Kaguya Ōtsutsuki, the first person to ever wield chakra, who can use just about any power to ever exist.
Who is truly the strongest? You be the judge.
As the main character, Naruto Uzumaki is naturally among the most powerful characters in the Naruto-verse. He has a nearly endless supply of chakra thanks to Kyuubi, the Nine-Tailed Fox that resides in his body. Though it takes him a ton of training and negotiating with Kyuubi, he is eventually able to harness its abilities as his own. But Naruto also has plenty of other techniques, including varying forms of Rasengan, a spinning ball of energy that he can launch at people, sage jutsu, which allows him to harness energy from the natural world, and countless other incredible abilities.
He's so strong that one wonders if it's actually physically possible for one person to be able to do so many things, even in a fantasy setting.
Kaguya Ōtsutsuki doesn't just wield the power of the Ten Tails, she is the Ten Tails. She's also the first person to ever use the power of chakra. She can absorb any chakra-based techniques she comes across, and just releasing a little bit of chakra can result in a massive shockwave. Madara is noted to be one of the strongest ninja in Naruto history, but Kaguya is more powerful than he is. She can harden her hair to such strength that it pierces Susanoo, a so-called ultimate defense, and she can manipulate her bones into offensive tools. She can travel to other dimensions and wield truth-seeking balls that are powerful enough to wipe out the universe.
These aren't even half of her abilities - if a power exists in the world, Kaguya probably has it. After all, she's the originator of all chakra.
There's a reason why a whole army went up against Madara. He not only possesses a wide plethora of jutsu, he can also easily throw hands with anyone who challenges him. In fact, he once said, correctly, that the only two people who ever presented a serious challenge to him were Hashirama and Guy. As a child, he was able to take on adult opponents without even awakening his Sharingan.
Later, he developed a wide range of abilities, including the ability to enter sage mode with no prior training, mastery of all elemental release techniques - one of which was granted by infusing his body with Hashirama's DNA - and a fully awakened Sharingan that was capable of putting the entire planet under mass hypnosis.
By the end of the series, Sasuke is so strong that the idea that anyone could possibly defeat him seems absurd. Even as a 12-year-old, he's a prodigy - he can spew giant fireballs out of his mouth, take on opponents in physical combat, and more. As he develops his skill set, he masters Orochimaru's cure seal techniques, acquires both the Mangekyou and the Rinnegan and all of the incredible powers that come with both of those highly sought-after eye-based powers. These include all of the powers Itachi had, plus abilities like traveling across different dimensions.
The only area in which Sasuke exhibits weakness is his emotional life - thanks to all the trauma he's experienced, he has difficulty connecting with others and managing his feelings.